Using the carbon coated expanded polystyrene (EPS) beads as filling admixture, the electromagnetic (EM) wave absorber more moistureproof and environment adaptive than the conventional absorber used in anechoic chamber was fabricated. The effective permittivity of the mixture with carbon volume content 1% was calculated by the strong fluctuation theory combining with Maxwell-Wagner theory; and the EM wave absorbing property of a laminated model filled with carbon coated EPS beads was predicted through calculation. Comparison with the experiment indicated that the results of calculation accorded with the experiment closely, and can be used for the design of the moistureproof EM wave absorber.